The invention relates to a mechanical shut-off system in the fuel supply system of a gas turbine, having a shut-off valve body which, by means of a spring, can be brought into a position interrupting a fuel line. The system further has a mechanism which, in the normal operation of the gas turbine holds the shut-off valve body in a position releasing the fuel line and releases the shut-off valve body in the event of damage or breakage of a structural element of the gas turbine. Such a mechanically operated shut-off system which, for example, in the event of a breakage of a gas turbine shaft, abruptly interrupts the fuel supply system of the gas turbine, according to existing regulations, must be provided, for example, on a flight gas turbine, and is known from British Patent Document GB-A-903 945 or U.S. Patent Document U.S. Pat. No. 3,050,939.
It is sometimes difficult to arrange these known shut-off systems, such that on a gas turbine, in the event of all possible damage cases or breaks on important structural components of the gas turbine, a secure interruption of the fuel supply takes place. The reason is that the corresponding mechanism which releases the shut-off valve body in the event of damage must definitely be impacted by the broken or damaged component.
In view of the above, it is an object of the present invention to provide a simple and reliable mechanical shut-off system. For achieving this object, it is provided that the mechanism is constructed as a shear-type (scissor-type) mechanism acted upon by a spring, which shear-type mechanism comprises an arm which is constructed such that, in the event of damage or a break of a structural element of the gas turbine, it is acted upon so that it releases the shut-off valve body.